A little info to help with your decision, the vast majority of the residential furnace blower motors are induction ac, no brushes to create a spark, and no start capacitor to connect and disconnect that could create a spark. I'm not saying that they are enclosed, or drip-proof, just that there is an extremely slim chance of that type of motor causing an explosion. I would bet that static electricity from plastic sheeting, dry conditions, or a light switch arcing has a higher chance of causing trouble.
